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[Python-Dev] PEP 342 support for string exceptions in throw()

Guido van Rossum guido at python.org
Sat Mar 25 00:04:11 CET 2006 
On 3/24/06, Phillip J. Eby <pje at telecommunity.com> wrote:
> At 02:36 PM 3/24/2006 -0800, Guido van Rossum wrote:
> >I think it's overkill to warn for any string exceptions thrown this
> >way. Since the only use case for using throw() is to pass an exception
> >you just caught, I don't see that putting the warning is useful --
> >it's just more code that in practice is never triggered.
>
> My proposal was that throw() should only succeed or fail, never warn.
>
> If you throw() a string exception with a traceback, it Just Works.
>
> If you throw() a string exception without a traceback, you get an immediate
> TypeError, just like in the 2.5 trunk now.
>
> Is that acceptable?  i.e., was that what you were "-0"-ing?

Actually that's slightly worse; I'm not sure we guarantee that
exceptions you catch *always* have a traceback object associated with
them. So -1.

> The only change is that throw() would now *accept* string exceptions
> without warning or error, if and only if you supply a traceback.  That is,
> if you are effectively re-raising an existing exception.

The current state is that it always allows them, right? I don't see a
reason to change that, and I don't think you've made a strong argument
for changing it -- I don't think the use case matters.

--
--Guido van Rossum (home page: http://www.python.org/~guido/)
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